In Third Generation Partnership Project (3GPP), frequency bands available for uplink transmission from a mobile terminal (also referred to as a “UE”) to a base station (also referred to as an “eNode B”) and downlink transmission from the base station to the mobile terminal are defined. In addition, carrier aggregation (CA) is under discussion to enable simultaneous use of a plurality of frequency bands (see Non-Patent Document 1).
It is known that unnecessary radiation such as an inter-modulation distortion (IMD) or a harmonic distortion occurs in a mobile terminal upon uplink transmission from the mobile terminal to a base station in a cellular system.
An IMD is an interference wave which occurs, when signals with two or more different frequencies coexist, on frequencies defined by the combination of the sums or the differences of these two or more different frequencies. When a plurality of frequency bands are simultaneously used according to carrier aggregation, an IMD occurs as a result of the combination of signals on these frequency bands.
A harmonic distortion is an interference wave which occurs on frequencies defined by multiples of a signal frequency. Not only when a plurality of frequency bands are simultaneously used according to carrier aggregation, but also when a single frequency band is used, a harmonic distortion occurs.